Lasers are often utilized in the processing of semiconductor substrates. Thermal processing, such as rapid thermal processing, is utilized to process substrates by changing the characteristics of the substrate being processes. The thermal processing may alter the physical structure of the substrate, implant dopants into the substrate, or melting a portion of the substrate.
Laser diodes are one example of a laser source for thermal processing. These lasers suffer from several disadvantages by requiring complicated cooling systems and a tendency to occasionally catastrophically fail. The failure of laser diodes, especially laser diode bars which are generally a plurality of laser diodes in series with one another, requires costly and time consuming maintenance. Additionally, the throughput of the thermal processing system is negatively affected when laser diodes fail. Moreover, conventional laser diodes must be utilized near or within a thermal processing chamber. The failure of the laser diodes with such proximity to the processing equipment can increase the probability of damage to other semiconductor processing components.
Another consideration in laser thermal processing is the ability of the laser source and associated optics to provide a desirable radiation profile to the substrate being processed. However, conventional laser diodes suffer from performance degradation over the useful lifetime of the laser diode. The decrease in performance often negatively affects the radiation profile and reduces the ability of the thermal processing system to effectively process the substrate in a desirable manner.
Therefore, there is a need in the art for a laser thermal processing apparatus which provides improved thermal processing characteristics. Additionally, there is a need for laser diode systems which are more easily maintained.